Fusible protector for a refrigeration system



June 30, 1964 A. COHEN 3,138,936

FUSIBLE PROTECTOR FOR A REFRIGERATION SYSTEM Filed Aug. 31, 1962 FIG. I

INVENTOR.

ARTHUR COHEN.

ATTORNEY.

Filed Aug. 31, 1962, Ser. No. 220,627 Claims. (Cl. 62-77) This invention broadly relates to a closed pressure system such as a refrigeration system, and more particularly to a refrigeration system of an air conditioning unit.

In a closed pressure system such as a refrigeration system the various components thereof are interconnected to form a closed path of flow for the refrigerant. As is known, the refrigerant circulating throughout the system undergoes changes in pase. In a closed system, representing as it does, a fixed volume, unexpected and abnormal conditions either interior or exterior of the system may cause refrigerant pressures to become far greater than that which the system may safely accommodate. For example, a great increase in the ambient temperature due, for example, to a-conflagration adjacent the system, results in a corresponding increase in refrigerant pressure. This increase in internal pressure in a closed refrigerant system may result in an explosion with consequent damage to or destruction of the system itself as well as possible injury to nearby personnel and damage to other adjacent structures.

It is a principal object of this invention to provide a unique refrigeration system construction which will unfailingly communicate the system to the atmosphere at a predetermined operating condition.

It is a further object of this invention to provide a novel closure apparatus for an emergency outlet in the closed refrigerating system of an air conditioning unit operable in response to predetermined temperature conditions to open the emergency outlet toreduce refrigerant pressure.

It is an additional object to provide a novel method of communicating a, closed refrigerant system to the atmosphere in response to a predetermined temperature to prevent system damage. Other objects will be readily apparent.

This invention relates to a closed pressure system including a conduit providing a path of fluid flow, an auxiliary outlet in the conduit adapted to communicate the system with the atmosphere, an impervious closure adapted to cover the auxiliary outlet, and temperature sensitive means operative to 'sealingly attach the closure to the conduit to tightly close the auxiliary outlet, the temperature sensitive means fusing at a predetermined temperature condition to release the closure so that the auxiliary outlet opens the system to the atmosphere.

The invention further relates to a method of protecting a refrigeration system comprising a compressor, a first heat exchange coil, a second heat exchange coil, and an expansion device interconnected to form a closed refrigerant flow path by suitable means including a conduit member, the steps which consist in: forming an outlet in the conduit member adapted to communicate the refrigerant system to the atmosphere, providing an impervious closure member having an area substantially greater than the outlet, applying a temperature sensitive bonding material to the closure member, the bonding material being operable to fuse at a predetermined temperature, covering the outlet by placing the closure mem ber thereover, heating the closure member to the predetermined temperature .to fuse the bonding material, and cooling the closure member below said predetermined temperature to solidify the bonding material whereby the closure member is sealingly attached to the conduit member to tightly close the outlet. The attached drawings A United States Patent 0 P re illustrate a preferred embodiment of the invention in which;

FIGURE 1 is a diagrammatic view of an air conditioning unit including a closed refrigerant system.

FIGURE 2 is an enlarged perspective view of applicants novel overload release structure; and

FIGURE 3 is a cross sectional view along lines IIIIII of FIGURE 2.

Referring more particularly to FIGURE 1, there is shown an 'air-to-air type air conditioning unit including a closed refrigeration system. In apparatus of this type, a first heat transfer coil is disposed within the area to be treated and a second heat transfer coil is located outside the area to be treated, usually in the ambient.

The unit includes a compressor 5 operatively connected to and driven by a motor 6. Compressor 5 discharges relatively hot gaseous refrigerant at a relatively high pressure through discharge line 11 to outside coil 10. Outside coil 10 functions as a condenser to condense the relatively high pressurized refrigerant gas to liquid as ambient air under the'influence of outside fan 32 flows over the surface of the outside coil extracting heat therefrom.

Liquid refrigerant formed in coil 10 passes through line 16 to. a suitable expansion device 15, shown in the form of a capillary tube. While a capillary tube has been shown, it is understood that other types of expansion means, for example, an expansion valve, may be utilized. The refrigerant thereafter passes through line 21 to inside coil 20. The refrigerant passing through inside coil 20 is converted to vaporous refrigerant as it.extracts heat for the stream of air flowing over the surface of the inside co'il under the influence of inside fan 31. The cooled air is thereafter directed by suitable means (not shown) into the area to be conditioned to cool the same. Vaporiz'ed refrigerant formed in coil 20 flows through suction line 25 into the compressorS to complete the refrigerant flow cycle 5 Inside and outside fans 31, 32 respectively may be driven from an electric motor 30. The motor 30, preferably a two speed motor, may have a double-ended shaft, the opposite ends of which mount inside and outside fans 31, 32 respectively.

Referring to FIGURES 2 and 3 of the drawings wherein applicants novel system relief structure is more particularly shown, a portion of the refrigerant suction line or conduit 25 is shown.

An opening or outlet 35 is suitably formed in conduit 25. Animpervious closure member 38 having an inner surface 39 bearing the same curvature as the outer surface 37 of conduit 25 is provided. Closure 38 is adapted to be placed on conduit 25 over opening 35. While arcuate closure 38 is illustrated as rectangular, other configurations, for example, round, may be employed.

To secure closure 38 to the outside surface 37 of conduit 25 over opening 35 in order that opening 35 may be tightly closed, inner surface 39 of closure 38 is provided with a solder composition 40. It is understood that outer surface 37 of conduit 25 proximate opening 35 may be provided with solder composition 40 in lieu of or in addition to the surface 37 of closure 38. Solder 40 is preferably a ternary eutectic solder which may be of the following analysis:

Percent Bismuth (Bi) 52.5 Lead (Pb) 32 Tin (Sn) 15.5

of the solder 40 thereto. The closure 38 is thereafter placed on the conduit 25 over the opening 35 so as to completely cover the same, the inner surface 39 thereof having solder 40 thereon resting on the outer surface 37 of conduit 25. Conduit 25 and closure 38 restingthereon are held in assembled position while closure 38 is heated by a suitable means. It is appreciated that conduit 25 may be heated in lieu of or in addition to closure 38. At a predetermined temperature, the solder composition 40 fuses or melts. The assembly is thereafter cooled. The now solidified solder 40 fixedly secures the closure 38 to the outside surface 37 of the refrigerant conduit or line 25 over opening 35 to tightly and sealingly close opening 35.

As may be understood closure 38 may be formed from various materials. It is preferred that the same material as the refrigerant part to which the closure is attached be used.

Referring to the air conditioning unit of the type shown diagrammatically in FIGURE 1 of the drawings, it is understood that the condition of the refrigerant within the system is influenced by ambient conditions proximate the unit. Thus, an increase in ambient temperature results in an increase in refrigerant temperature and therefore refrigerant pressure. A large increase in ambient temperature due for example to a fire at or closely adjacent the unit may create an explosive condition within the closed system due to the high refrigerant pressure resulting therefrom. This danger is obviated by applicants unique construction in that at a predetermined temperature, which represents the safe pressure-temperature limit for the system, the solder composition 40 fuses or melts. When the source of the high temperature, while proximate a portion of the unit, is nevertheless removed from applicants pressure relief structure, the increase in temperature is reflected in the relief structure area. This is due to the excellent thermal conductivity of the commonly used copper refrigerant tubing and/ or because of the resulting high refrigerant pressure in the system which results in high refrigerant temperature. The fusing of the solder bond between the closure 38 and refrigerant conduit 25 releases the closure. As may be appreciated, the pressurized refrigerant within conduit 25 removes closure 38 to communicate refrigerant conduit 25 With the atmosphere by means of opening 35. With the refrigerant system now open to the atmosphere, pressure within the system is rapidly reduced. Any potential danger due to an excessive refrigerant pressure is obviated.

While applicants novel apparatus and method of refrigerant system protection has been disclosed in combination with the refrigerant suction line, it is appreciated that applicants invention is not limited thereto. Other locations in the refrigeration circuit may be contemplated as, for example, on the refrigerant liquid line 16.

As may be appreciated, the composition of solder 40 is such that the solder will fuse r melt at a predetermined temperature to release the closing member. The predetermined fusing temperature may be varied by the use of solders having different chemical compositions.

While I have described a preferred embodiment of the invention, it will be understood the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

I claim:

1. The method of protecting a refrigeration system including a compressor having a suction side and a discharge side and having means including a conduit member operatively connecting said compressor suction side and discharge side in a closed refrigerant system including a first coil, a second coil and an expansion means, the steps which consist in: forming a relief outlet in the conduit member adjacent the compressor suction side adapted to communicate the refrigerant system with the atmosphere, providing an impervious closure member of an area substantially greater than the relief outlet and having a configuration substantially compatible with the shape of the conduit member so that a surface of the closure member tightly abuts the surface of the conduit member circumjacent the relief outlet, applying a eutectic solder to one of said surfaces, said eutectic solder having a predetermined fusing temperature, covering the relief opening by placing the closure member thereover, heating one of said members to the predetermined temperature to fuse said eutectic solder, and cooling said one member below the predetermined temperature to solidify said eutectic solder to tightly fix the closure member to the conduit member so that said relief outlet is closed.

2. The method of protecting a refrigeration system as recited in claim 1 including the step of applying the eutectic solder to the surface of the closure member.

3. The method of protecting a refrigeration system as recited in claim 1 including the step of aplying the eutectic solder to the surface of the conduit member circumjacent the relief outlet.

4. The method of protecting a refrigeration system as recited in claim 3 including the step of treating the surface of the conduit member circumjacent the relief outlet with a flux.

5. In combination with a refrigeration system including a compressor, an evaporator, a condenser and expansion means operably connected by suitable pipe lines to form a closed pressure system, protective means for said system comprising an auxiliary outlet in one of said pipe lines, a closure for said outlet having an arcuate configuration compatible with the pipe line containing said outlet and being larger than the outlet so that engagement between the closure and the pipe line is limited to the peripheral portion of the closure and the portion of the exterior surface of the pipe line surrounding said outlet, a fusible bonding material interposed between the closure and the pipe line for attaching the closure securely to the pipe line thereby preventing escape of refrigerant through the outlet, said bonding material being responsive to a predetermined temperature condition within the refrigeration system and adjacent the closure to release the closure from the pipe line to open the outlet.

References Cited in the file of this patent UNITED STATES PATENTS 231,713 Grinnell Aug. 31, 1880 2,019,421 Link Oct. 29, 1935 2,220,299 Stover Nov. 5, 1940 OTHER REFERENCES Handbook of Chemistry and Physics, Thirty-first edition, Chemical Rubber Publishing Company, 2310 Superior Street, Northeast, Cleveland, Ohio, page 1292. 

1. THE METHOD OF PROTECTING A REFRIGERATION SYSTEM INCLUDING A COMPRESSOR HAVING A SUCTION SIDE AND A DISCHARGE SIDE AND HAVING MEANS INCLUDING A CONDUIT MEMBER OPERATIVELY CONNECTING SAID COMPRESSOR SUCTION SIDE AND DISCHARGE SIDE IN A CLOSED REFRIGERANT SYSTEM INCLUDING A FIRST COIL, A SECOND COIL AND AN EXPANSION MEANS, THE STEPS WHICH CONSIST IN: FORMING A RELIEF OUTLET IN THE CONDUIT MEMBER ADJACENT THE COMPRESSOR SUCTION SIDE ADAPTED TO COMMUNICATE THE REFRIGERANT SYSTEM WITH THE ATMOSPHERE, PROVIDING AN IMPERVIOUS CLOSURE MEMBER OF AN AREA SUBSTANTIALLY GREATER THAN THE RELIEF OUTLET AND HAVING A CONFIGURATION SUBSTANTIALLY COMPATIBLE WITH THE SHAPE OF THE CONDUIT MEMBER SO THAT A SURFACE OF THE CLOSURE MEMBER TIGHTLY ABUTS THE SURFACE OF THE CONDUIT MEMBER CIRCUMJACENT THE RELIEF OUTLET, APPLYING A EUTECTIC SOLDER TO ONE OF SAID SURFACES, SAID EUTECTIC SOLDER HAVING A PREDETERMINED FUSING TEMPERATURE, COVERING THE RELIEF OPENING BY PLACING THE CLOSURE MEMBER THEREOVER, HEATING ONE OF SAID MEMBERS TO THE PREDETERMINED TEMPERATURE TO FUSE SAID EUTECTIC SOLDER, AND COOLING SAID ONE MEMBER BELOW THE PREDETERMINED TEMPERATURE TO SOLIDIFY SAID EUTECTIC SOLDER TO TIGHTLY FIX THE CLOSURE MEMBER TO THE CONDUIT MEMBER SO THAT SAID RELIEF OUTLET IS CLOSED. 